Thread brake for shuttles, particularly of shuttle embroidering machines



Nov. 13, 1934. A. MEIER 1,980,544

THREAD BRAKE FOR SHUTTLES, PARTICULARLY 0F SHUTTLE EMBROIDERING MACHINES Filed Dec. 5, 1933 vi WkM Patented Nov. .13, 1934 UNITED STATES THREAD BRAKE FOR SHUTTLES, PARTICU- LARLY OF SHUTTLE EMIBROIDERING MACHINES Adolf Meier, Weinfelden, Switzerland Application December 5, 1933, Serial No. 701,014 In Switzerland December 31, 1932 3 Claims.

This invention relates to thread brakes for shuttles particularly of shuttle embroidering machines, wherein the braking pressure exerted by a braking arm on the shuttle thread is regulat- 5 able. In arrangements of this kind, it is customary to use as a braking arm an elongated leaf spring which acts on the thread in the direction towards the cover of the shuttle and is adapted to be influenced by means of a rockable pressure arm for regulating the braking pressure, i. e. the thread tension. Furthermore, an arrangement is known wherein the leaf spring is curved in a bowed form to correspond to the path of movement of the pressure arm, thus providing for a longer ascending cam face between the pressure arm and the braking spring. By this measure, the braking spring is shortened which tends to render the braking effect less smooth and regular than the braking effect obtainable by means of a longer braking spring.

In both known arrangements referred to above, the adjustment of the pressure arm is effected entirely arbitrarily and is complicated by the fact that the thin pressure arm offers but little free J; space for grasping the same, this being ordinarily accomplished by applying a finger nail or in a similar manner, wherefrom very often injuries of the hand accrue when the finger nail slips on. Moreover, it frequently happens that the spring breaks, as the curvature of the same must be readjusted every time the magnitude of pressure is changed by rocking movement of the pressure arm, with a View to obtaining at all times an effective braking path adapted to impart a uniform thread tension, which adjusting operation is complicated and time-wasting.

According to this invention these drawbacks are eliminated in the thread brake by forming a braking face perpendicularly disposed to the 'cover of the shuttle by means of a circumferential flattening of a freely rotatable abutment memher, for the thread to pass over, this braking face cooperating with a substantially straight elastic braking arm which is adapted to be influenced from the opposite side by means of a circumferentially ascending cam face of a regulatable pressure element arranged to be rotatably adjustable with the aid of a scale.

The circumference of the pressure element forms a relatively long ascending cam face for cooperation with the braking arm which provision in conjunction with the scale renders possible an accordingly fine gradual regulation of the thread tension under perfectly perspicuous conditions. The pressure element is advantageously adapted to be readily adjusted by means of a' blade insertable in a front slot of this element, the changing over from a certain magnitude of thread tension to another thus being quickly and reliably performable in a simple manner. The freely rotatable abutment member provided for the braking arm adjusts itself according to requirements and forms an effective braking path of permanently constant length, thus being adapted to maintain the thread tension uniform at any magnitude of the same. The individual parts of the brake can be manufactured by quantity production as congruent parts of a definite shape which is not the case when curved leaf springs are involved. Again, it is possible to regulate or change over respectively in a most simple manner the brakes of any number of shuttles from the start or at any time thereafter so as to effect a required uniform thread tension throughout.

The rotatably adjustable pressure element is advantageously provided with a circumferential flattened portion which permits of retracting the pressure arm from the abutment member in order to permit of threading up the brake unhindered. Furthermore, the braking arm is advantageously inserted in a recess of the cover of the shuttle and adapted to grip behind the pivot of the cover which arrangement facilitates the mounting and occasional exchanging of the braking arm.

In the accompanying drawing a constructional form of the invention is illustrated by way of example only, in which Fig. 1 shows a longitudinal section of a shuttle provided with a thread brake according to the invention,

Fig. 2 shows a top plan view 'of Fig. 1,

Fig. 3 shows a fragmentary sectional view on the line IIIIII in Fig. 2 of the shuttle cover carrying the thread brake, and

Fig. 4 is a similar view on the line IV--IV of Fig. 2.

On the shuttle 1 is rockably mounted, on a cross pivot 2 thereof, the cover 3 of the shuttle. A rod-shaped straight elastic pressure arm 4 bears with one of its sides against the top of the cover 3. This arm of a square cross section is inserted at one end in a corresponding recess 4 in a hinge socket of the cover 3 so as to surround the pivot 2 in the manner of a loop. The elastic arm 4, thus connected to the cover 3 for common rocking movement, is urged with one side of its outer end portion on an abutment ring 5 which opposes to the arm 4 a rectilinear engagement face 6 formed by a circumferential flattening so as to constitute a braking face for the thread 9 of a perpendicular disposition to the cover 3 of the shuttle.

This pressure or braking face 6 is topped over at the side remote from the cover 3 by a flat ledge '7 formed on the head of a holder 8, connected to the cover, at a position corresponding to said flattening. The abutment ring 5 is mounted for free rotation on the cover 3 by means of the holder 8. The thread 9 inserted between the arm 4 and the lateral guide ring 5, for the purpose of being braked While unwinding, is prevented from skipping the brake by the ledge 7. After being with drawn from the spool 10 inserted in the shuttle 1, the thread 9 passes through apertures 11 and 12 situated in the cover 3 ahead and behind the trapping or braking position respectively to sub sequently leave the shuttle 1 through a lateral aperture 13.

The arm 4 is influenced on its side opposite to the brake by an ascending cam face of a pressure member 14 arranged on the cover 3 so as to be adapted to press said arm against the abutment ring 5. This pressure member 14 acts on the middle portion of the length of the spring arm 4 by means of an eccentric circumferential face 14, so that depending on the rotational adjustment of the rotatable pressure member 14 more or less pressure is exerted on the elastic arm 4 and thereby a corresponding braking effect is imparted to the unwinding thread 9. For the purpose mentioned above, the pressure member 14 can be rotationally adjusted by means of an implement or the like adapted for insertion in the front slot of this member. The extent of adjustment of the pressure member 14 and thus the degree to which the thread tension is regulated is controllable by means of a scale provided on the pressure member 14 and comprising the numbers 1 to 4, so that the relative position of this scale to the point of contact between the pressure member 14 and the spring arm 4 or any other suitable marked point respectively can be read off. For securing the pressure member 14 on the cover 3 or in its respective position of adjustment, a springy annular disc 15 (Fig. 3) sunk in the cover 3 (Fig. 3) is provided which is gripped behind by a head 16 of the pressure member 14.

Due to the abutment ring 5 being rotatably arranged, this ring is adapted to adjust its engagement 6 at all times automatically in register with the arm 4, the positioning of which is defined by the pressure exerted on the same by the pressure member 14. In this Way provision is made for an effective braking path of permanently constant length, the capacity of regulating the thread tension of the abutment ring 5 thus being also constant in any position of this ring. The pressure engagement face 6 of the abutment ring 5 is of such length that all occasional inequalities in the evenness of the thread are bridged over by this face, i. e. by the thread brake, so that the thread passing through the brake is imparted a continually uniform tensioning.

The pressure regulating element 14 is provided 5:- with a circumferential flattened portion, as evi-.

dent from Fig. 2, which, when the pressure regulating element is correspondingly adjusted, permits of retracting the braking arm 4 from the abutment 5, so that the thread can be introduced into the brake unhindered.

The braking arm thus being connected to the shuttle by more insertion in a recess of-the shuttle cover 3 and hooking to the pivot 2 of the shuttle cover, is readily demountable or interchangeable respectively upon requirement.

I do not limit myself to the particular size, shape, number or arrangement of parts as shown and described, all of which may be varied without going beyond the scope of my invention as shown, described and claimed.

What I claim is:

1. In a thread brake for shuttles particularly of shuttle embroidering machines, in combination, a shuttle, a cover for said shuttle, an abutment member mounted for free rotation on said cover, a flat braking face on said abutment member perpendicularly disposed to said cover in the path of the thread unwinding from said shuttle, a substantially straight elastic pressure arm adapted to cooperate with said flat braking face for braking engagement with said thread, a rotatable and angularly adjustable pressure element coopcrating with said pressure arm in opposed relationship to said abutment member and urging said pressure arm towards said braking face to exert a regulatedpressure effect onsaid thread, and a scale provided on said pressure element for indicating the magnitude of the pressure adjusted.

2. In a thread brake for shuttlesparticularly of shuttle embroidering machines in combination, a shuttle, a cover for said shuttle,-an abutment member mounted for free rotation on said cover, a braking face on said abutment member perpendicularly disposed to said cover in the path of the thread unwinding from said shuttle, a sub stantially straight elastic pressure arm for braking engagement with said thread, means for fastening said pressure arm to said shuttle cover to adapt said arm to confrontsaid braking face for pressing said thread thereagainst, a rotatable pressure element, a circumferentially ascending cam face on said element cooperating with said pressure arm in opposed relationship to said abutment member, a circumferential flattened portion on said rotatable pressure element adapted to be turned into juxtaposition to said pressure arm for retracting the same from said braking face for facilitating the threading up of the thread brake, means for rotatably adjusting said pres-- sure element for urging said pressure arm towards said braking face to exert a regulatedlpressure effect on said thread, anda scale provided on said pressure element for indicating the magnitude of the pressure adjusted.

3. In a thread brake for shuttles particularly of shuttle embroidering machines, in combination, a shuttle, a cover for said shuttle, a pivotal connection between said shuttle and' said cover, said cover having a recess adjacentsaid pivot, an abutment member mounted for free rotation on said cover, a braking face on said abutment member perpendicularly disposed tosaid cover in the path of the thread unwinding from said shuttle, a substantially straight elastic pressure arm for braking engagement with said thread inserted in the recess of said cover adjacent said pivot and surrounding said pivot in the manner of a loop. so as to be adapted .to confront said vided on said pressure element for indicating.

the magnitude of the pressure adjusted.

- ADOLF MEIER... 

